Family Sharing setup
Husband received the email that said he had been invited to family sharing. He can not see how to "accept" the invitation.
Within the email or message should be a link to join -- Set up Family Sharing - Apple Support.
"If your family member is with you, they can enter their Apple ID password on your device to accept the invitation. You can also send them an invitation, and they can accept from their device. If you have multiple Apple IDs in the iTunes Store and the App Store, you can invite each of your accounts to the group, so you can share purchases from your other Apple IDs with your family."